This invention pertains to a vacuum load-break switch having a unique combination of features.
Vacuum interrupters have been used for load-break switches in the prior art, but not with a groundable disconnect switch in series. Circuit breakers use a different type of vacuum interrupter, can be opene load-break device. One important reason for using vacuum interrupters is their ability to interrupt full load current twenty thousand times while ordinary loadbreak switches will interrupt rated current a maximum of one hundred times.
The vacuum interrupters used for load-break applications cannot interrupt the high levels of current required for circuit breakers. However, the circuit breaking vacuum interrupters cause voltage transients and the system must be protected against the transients. Also, the cost of the circuit-breaking type of vacuum interrupter is several times that of the load-break type vacuum interrupter.